A person can live without a natural heart, but only through the use of sophisticated mechanical technology. The human heart functions fundamentally as the body’s pump, and without a working natural one, a machine must step in immediately to assume this role. This mechanical intervention is the only way to sustain life once the organ responsible for circulation has failed completely. This proves that the function of the heart, not the organ itself, is non-negotiable for survival.
The Biological Necessity of the Heart
The heart’s primary role is to create a pressure gradient that drives blood through the circulatory system. This continuous pumping action ensures systemic circulation, delivering oxygen and nutrients to every cell in the body. Oxygen-rich blood must be pushed with enough force to overcome the resistance of the blood vessels and reach the farthest tissues. Without this sustained pressure, organs like the brain and kidneys quickly suffer irreversible damage.
The pump must operate constantly to facilitate the exchange of gases and the removal of metabolic byproducts. Deoxygenated blood, carrying carbon dioxide and other wastes, returns to the heart to be sent to the lungs and then the kidneys and liver for processing. The heart effectively divides the circulation into two loops: one to the lungs for oxygenation and one to the rest of the body. Failure in this mechanism means waste accumulates and the body’s cells are starved of necessary resources.
Mechanical Devices for Total Circulatory Support
Survival without a natural heart is made possible by a device called a Total Artificial Heart (TAH). This technology is distinct from Ventricular Assist Devices (VADs), which only support a failing heart by helping one or both of its lower chambers. A TAH is implanted after a surgeon removes the native ventricles, the two main pumping chambers of the heart, making it a complete replacement for the biological organ’s function.
The TAH consists of two mechanical ventricles and four mechanical valves that work similarly to the heart’s natural valves, directing blood flow into the lungs and the rest of the body. The entire system is powered and controlled by an external machine, often called a driver, which the patient must carry. This external driver uses compressed air to inflate and deflate the artificial ventricles, mimicking the contraction and relaxation cycle of a biological heart.
The TAH connects directly to the patient’s remaining upper heart chambers, the atria, and to the major arteries. Most TAHs are used as a “bridge to transplant,” meaning they sustain the patient until a suitable donor heart becomes available. However, they allow a person to live and function with a fully removed and replaced biological heart.
The Concept of Living Without a Pulse
Many modern mechanical circulatory support systems, including some TAHs and most continuous-flow VADs, circulate blood without generating a traditional pulse. The natural heart creates a pulsatile flow, where blood pressure rises with each beat and falls in between. Continuous-flow pumps, conversely, use a rapidly spinning rotor to move blood at a constant speed, resulting in a steady, non-pulsatile flow.
This lack of a rhythmic pressure wave means that patients with these devices may not have a detectable pulse when a doctor checks their wrist or neck. The continuous flow generated by the pump is sufficient to perfuse the organs and keep the patient alive. However, this unique physiology presents challenges for medical professionals, as traditional methods of measuring blood pressure become unreliable.
The absence of pulsatility has raised questions about its long-term effects on the body’s vascular system. The continuous flow can alter the structure of the blood vessels over time and is sometimes linked to complications like gastrointestinal bleeding. Despite these issues, the ability of the continuous-flow devices to maintain life confirms that the constant movement of blood, rather than the rhythmic pulse itself, is the primary requirement for survival.
The Realities of Life with Artificial Circulation
Living with a Total Artificial Heart imposes significant lifestyle changes and requires constant maintenance. The patient is permanently attached to the external driver, which is a portable machine that can weigh around 14 pounds and is typically carried in a backpack or shoulder bag. This driver provides the power and control necessary to keep the internal pump functioning at all times.
The connection between the internal device and the external driver involves tubes, or drivelines, that pass through the skin of the abdomen. These openings create a permanent pathway for bacteria, making the risk of infection a constant concern. Patients must adhere to strict hygiene protocols and often take long-term antibiotics to mitigate this danger.
In addition to the infection risk, the presence of mechanical parts in the circulatory system increases the likelihood of blood clot formation. This necessitates a rigorous, lifelong regimen of anticoagulation therapy, commonly known as blood thinners. The combination of external equipment, infection risk, and specific medication requirements means that while the TAH restores physical strength and circulation, it also introduces complex dependencies and limitations on daily life.